The present invention relates a dispenser for supplying drinking water, and more particularly to a drinking water dispenser which can always supply hot water and chilled water. Further, it is arranged to enable heat sterilization of storage tanks and a piping system in the dispenser and to suppress the microorganisms invasion of the dispenser. This arrangement improves the degree of safety in disinfection control and maintains natural character of the drinking water supplied from the dispenser. Furthermore, this improves an operational ability such as an installation of the drinking water container and the size of the dispenser.
Various types of a dispenser for supplying drinking water have been already marketed. According to the increase of users' interest with respect to drinking water, the demands to ensure safety of drinking water and to pursue the quality in natural character of drinking water have been increased. As to ensuring safety of drinking water, in case of a dispenser for supplying tap water, since the tap water has some sterilization function by means of remained chlorine added in the tap water for disinfection, the growth of the microbe in the tap water is suppressed and therefore the ensuring of the safety is kept.
However, in case of drinking water such as natural mineral water, since chlorine for disinfection is not added in the drinking water, it is important to take account of the growth of microbe in the drinking water. The growth of microbe in the drinking water is harmful if the microbe is pathogenicity. Even if the microbe is not pathogenicity, it may apply strange taste and odor to the drinking water or make the drinking water turbid. The growth of microbe in the dispenser is prevented by always continuously supplying the drinking water. However, if the drinking water rested in the dispenser for a long time such as a night or week end in case of use in an office, there is a possibility that microbe grows in the drinking water. Also, the colony of microbe may grow in the dispenser as a result of long term use.
Conventionally, in order to suppress the growth of microbe in the dispenser, there have been proposed a lot of dispensers which are arranged to execute sterilization by pouring germicide or high-temperature water from external to a piping system thereof and by circulating it, or dispensers which are arranged to provide a filtering device for removing microbial contaminants therefrom. However, pouring germicide or high-temperature water into the piping system of the dispenser requires providing an apparatus for pouring such germicide in the dispenser and for discharging it after the circulation and a space for pouring and discharging such germicide. Further, the operation thereof is complicated and takes predetermined time. Furthermore, after the use of germicide, it was necessary to wash the germicide out. In case of a filtering apparatus, maintenance of a filter thereof is complicated and there is a problem that the microbe caught by the filtering apparatus may grow and increase colony in the filtering apparatus.
Therefore, the inventors of the present invention have proposed a dispenser for supplying drinking water from a previously drinking water packaged container, as disclosed in Japanese Patent Provisional Publication No. 6-48488. The proposed drinking water dispenser comprises a cooling system for cooling a drinking water packaged container and a tank for storing drinking water in a piping system and a sterilization system for executing heat sterilization of the piping system by means of a heater used heating device or hot water flowing device. Such a heat sterilization system is controlled by an automatic execution device. By the provision of this sterilization system, the drinking water dispenser sterilizes microbe grown in the dispenser, provides a simple and effective sterilization method and supplies safety guaranteed drinking water usually set in hot or chilled condition.
However, since this conventional drinking water dispenser is arranged to have a heater in each of a piping system, a cool water tank and a hot water tank, it is necessary to ensure a large space for the heaters and to consume lot of electric power. Accordingly, this invites the increase of the cost for producing the dispenser and of the running cost of the dispenser. Although the heat sterilization method of this conventional drinking water dispenser functions effectively as a sterilization method having sufficient merits, there is a part which is not heated due to the detailed structure of the conventional dispenser. Therefore, the sterilization thereof has been sometimes executed insufficiently. For example, the conventional drinking water dispenser is arranged to connect the portions from the drinking water container to the piping system by means of I-type joints. Although this joint is usually employed to facilitate the arrangement of hoses and to simplify the structure in the dispenser, the hot water does not flow through the I-type joint itself and therefore the I-type joint is not heat sterilized by the hot water.
Generally, in case of the contaminating of a small amount of microbe or contaminating of non disease-causing microbe, the safety of the drinking water is ensured by heat sterilizing the microbe contaminated in the dispenser. However, in case of the contaminating of a lot of microbe or contaminating of pathogenic microbe, the safety of the drinking water is degraded by the contaminating of the microbe, and the quality in natural character of the drinking water may be degraded. In order to keep the safety and the quality in the natural character of the drinking water, it is necessary to provide a sterilization means which prevents the contamination of microbe into the dispenser as possible and avoids heating sterilization from being frequently executed. Further, it is necessary to facilitate the maintenance of the dispenser and to prevent the degradation of each part of the dispenser. Furthermore, in case that the dispenser is used as a dispenser for supplying drinking water, more particularly, in case that it is used as a dispenser for supplying drinking water which has a very delicate taste and odor and tends to be affected in natural character like as natural mineral water, it is important to pay attention to a slight addition of the strange taste and odor from parts contacted to the drinking water. Furthermore, the dispenser is required to have a good controllability, to be treated easily and to have a compact appearance which does not require a large space.